I have a Gigabyte X85A-UD3R motherboard with an ICH10R. I also have a RAID 0 (striping) setup of 2x1TB disks, configured at the BIOS level (raid controler which boots before OS/after BIOS?) which merges the two physical volumes into one 2TB volume labelled MainVolume. The volume contains four primary partitions - two for Windows (boot and data) and two for Linux (root and swap), no logical partitions.

I had problems installing any Ubuntu after 10.04 on this setup. In fact, I installed 12.04 by installing 10.04 first and then upgrading. Ubuntu 10.04 worked flawlessly, but after upgrade to 12.04 it always displayed a message during boot in the console, something like "iwatch dm-5 failed" (not sure), but I didn't pay much attention to it because the system worked. Up until today's upgrade to 12.10.

Today when I upgraded to 12.10 at the end of the upgrade process it tried to install grub, and failed with the message:

Path `/boot/grub' is not readable by GRUB on boot. Installation is impossible. Aborting.

Then the upgrade manager offered me to select a destination for GRUB - sda, sdb or MainVolume. When I select MainVolume it falls back to the above error message and asks again. I didn't choose sda or sdb, because I thought it might write to the physical drives as non-striped and mess up existing partitions. In the end I chose not to install grub and completed the upgrade.

I'm writing this now from that box which I don't dare to reboot since it might not boot.

@K.KPatel: I don't see your post even mention fakeraid/dmraid... What makes you think it's a duplicate, the fact that grub-install fails? It can fail for any number of reasons.
–
Boris B.Oct 23 '12 at 20:46

I had a very similar issue. I upgraded from 12.04 to 12.10 and after the install I had the same issues as you. I've spent hours messing with various things trying to get this resolved, complicated by the fact that I currently can't boot from DVD/CD and my largest functional USB key that my main board will boot is < 120mb.

Finally I went back to trying super grub2 disk again and tried booting into Ubuntu using the 3.5.0-17-generic kernel instead of the 3.2 kernel I was previously on. Earlier, I was unable to boot that kernel due to it hanging before loading completely (I can't remember what exactly caused the hang) but it finally let me boot. I was then able reinstall grub-pc & dependencies as normal. Make sure you have some way to chainload into your install on the 3.5 kernel and maybe you'll be able to reinstall grub.

Yes, it seems that the distribution upgrade script does not play nice with RAID0. I had a simple fresh 12.04 install with two SSDs as a single RAID0 drive, grub installation failed in a similar manner. Booting with a USB drive and using the boot-repair tool to reinstall GRUB resolved the problem.